Dementia may not pose as terrible a threat to the world’s ageing population as many have assumed. Recent research suggests that the risk of developing Alzheimer’s and other degenerative brain diseases as an individual grows old has decreased in recent decades. The latest evidence for declining age-specific incidence of dementia comes as the pharmaceutical industry celebrates the first demonstration of drugs to slow the progression of the disease. Biotech researchers are also making progress towards diagnostic tests to detect biological changes at a pre-symptomatic stage, when the onset of mental deterioration might be prevented.
These glimmers of hope are no reason for complacency. Even taking an optimistic view that incidence continues to decline, demographic factors will add tens of millions more dementia cases to the current total estimated by the World Health Organization at 55mn. Rather, they should be a stimulus for redoubled global action to build on recent scientific success, with more resources directed to understanding the underlying causes of dementia, with a view to preventing cases before they need treatment.
In addition to research into the detailed biology of neurodegeneration, more large-scale studies are needed at the population level to investigate the environmental and lifestyle factors that increase or decrease susceptibility to dementia. This epidemiological approach, relatively neglected so far, will require substantial new funding from governments and charities.